|
Carbon
Dioxide Levels and Ventilation Rates in Schools
David A. Coley and Alexander Beisteiner
Centre for Energy and the Environment, University of Exeter, Physics
Building
Stocker Road, Exeter EX4 4QL, UK
Abstract
In the following,
measurements of CO2 levels in seven classrooms in four schools
are reported. Measurements were taken for approximately one week in each
classroom during the heating season and the time-varying ventilation rates
estimated. The results of the experiments show CO2
concentrations which are far beyond the guideline value of 1000 ppm (the
average concentration during the occupied period was 1957 ppm). In
some classrooms the level exceeded the range of the detector (4000ppm).
Calculated air supply rates vary from unacceptably low levels to rates
which are in line with guidance (the average occupied rate was 0.84 ac/h
or 1.38 l/s.p). The occurrence of periods with acceptable supply
rates, and the rates found during purge ventilation, show that the
surveyed classrooms have the potential to provide adequate fresh air.
Anecdotal evidence from the classroom teachers suggest that the reason
enough fresh air is not being provided is the reluctance of staff to open
windows: firstly because of the draughts this might cause, and secondly,
because they are unaware of a problem.
Key words: schools, carbon dioxide, ventilation rate
|
